Inconsistency often arises in real-world databases and, as a result, critical queries over dirty data may lead users to make ill-informed decisions. Functional dependencies (FDs) can be used to specify intended semantics of the underlying data and aid with the cleaning task. Enumerating and evaluating all the possible repairs to FD violations is infeasible, while approaches that produce a single repair or attempt to isolate the dirty portion of data are often too destructive or constraining. In this thesis, we leverage a recent advance in data cleaning that allows sampling from a well-defined space of reasonable repairs, and provide the user with a data management tool that gives uncertain query answers over this space. We propose a framework to compute probabilistic query answers as though each repair sample were a possible world. We show experimentally that queries over many possible repairs produce results that are more useful than other approaches and that our system can scale to large datasets.

Formate-based mud has been used to drill deep gas wells in Saudi Arabia since 2004. This mud typically contains XC-polymer, starch, polyanionic cellulose, and a relatively small amount of calcium carbonate particles, and is used to drill a deep sandstone reservoir (310°F). Calcium carbonate particles are frequently used as weighting material to maintain the pressure that is required for well control and minimize the leak-off. Such solids become consolidated and trapped in the polymeric material and this makes the filter cake a strong permeability barrier. Various cleaning fluids were proposed to remove drilling mud filter cake; including: solid-free formate brine and formate brine doped with organic acids (acetic, formic, and citric acids), esters, and enzymes. The main objective of this research is to assess the effectiveness of these cleaning fluids in removing drilling mud filter cake. A dynamic high-pressure/high-temperature (HPHT) cell was used to determine characteristics of the drilling mud filter cake. Drilling mud and completion fluids were obtained from the field. Compatibility tests between potassium formate brine, cleaning fluids, and formation brine were performed at 300ºF and 200 psi using HPHT visual cells. Surface tensions of various cleaning fluids were also measured at high temperatures. The conventional method for cleaning the filter cake is by circulating solid-free formate brines at a high flow rate. This mechanical technique removes only the external drilling fluid damage. Citric acid at 10 wt%, formic acid, and lactic acid were found to be incompatible with formate brine at room temperature. However, these acids were compatible with formate brine at temperatures greater than 122°F. Only acetic acid was compatible with formate brine. A formula was developed that is compatible at room and reservoir temperature. This formula was effective in removing filter cake. A corrosion inhibitor was added to protect downhole tubulars. In general detail, this research will discuss the development of this formula and all tests that led to its development.

This study was conducted to develop and validate cleaning procedures for different processing equipment of varying complexity and to determine the efficacy of two different allergen tests. Following introduction of selected allergens to processing equipment, two treatments were applied - water wash or scrub/sanitize ? and a no clean was also evaluated. The equipment used consisted of a slicer, grinder, injector, vacuum tumbler, and plastic lugs. To introduce the allergen to the slicer, nine ready-to-eat hams were used. One hundred twenty-two kilograms of pork trim were ground, and a milk allergen was incorporated into the meat. The injector was contaminated with a food allergen by injecting boneless pork loins with a marinade containing soy flour. The slicer, grinder, injector, tumbler, and lugs were then subjected to randomized treatments. The results showed that the water wash and scrub/sanitize treatments did not differ significantly among the pieces of equipment tested. This study supported that both water wash and scrub/sanitize treatments can effectively removed allergens to a level below the industry threshold of 5 ppm.

Produced water is a major waste produced from oil and natural gas wells in the state of Texas. This water could be a possible source of new fresh water to meet the growing demands of the state after treatment and purification. This thesis describes a research project that evaluated the treatment of brine generated in oil fields (produced water) with ultrafiltration membranes. The characteristics of various ultrafiltration membranes for oil and suspended solids removal from produced water were studied to test whether they could be used in a pretreatment method. The research measured the effect of pressure and flow rate on performance of three commercially available membranes for treatment of oily produced water. Oil and suspended solids removal were measured by using turbidity and oil in water measurements taken periodically. The study also analyzed the flux through the membrane and any effect it had on membrane performance. The research showed that an ultrafiltration membrane provided turbidity removal of over 99% and oil removal of 78% for the produced water samples. The results indicated that the ultrafiltration membranes would be useful as one of the first steps in purifying the water. Membrane cleaning of produced water-fouled membranes by micellar solutions was investigated. A neutral pH and ambient temperature micelle solution for effective cleaning of oily water-fouled membranes was developed and studied. The performance of cleaning solutions on ultrafiltration membranes was investigated on laboratory size membrane testing equipment. Different micro emulsion solutions were studied to evaluate the effect of solution properties on cleaning performance. Three types of multiple membranes were studied, each having the same polyvinylidene fluoride (PVDF) material but with different nominal separation or flux characteristics. The data showed that the use of a micelle solution to clean the produced water-fouled membranes was a feasible and effective method. The study showed with further adjustment of the micelle solution the cleaning effectiveness could be optimized to provide double the effectiveness of current industry methods for membranes fouled by produced water.

Megasonic cleaning is routinely used in the semiconductor industry to remove particulate contaminants from wafer and mask surfaces. Cleaning is achieved through proper choice of chemical solutions, power density and frequency of acoustic field. Considerable work has been done to increase understanding of particle removal mechanisms in megasonic cleaning using different solution chemistries with varying ionic strengths. However, to date, the focus of all these studies of particle removal has been either cavitation or acoustic streaming.The propagation of sound waves through a colloidal dispersion containing ions is known to result in the generation of two types of oscillating electric potentials, namely, Ionic Vibration Potential (IVP) and Colloid Vibration Potential (CVP). These potentials and their associated electric fields can exert forces on charged particles adhered to a surface, resulting in their removal. In addition, the pressure amplitude of the sound wave is also altered in solutions of higher ionic strengths, which can affect the cavitation process and further aid in the removal of particles from surfaces. To test the two hypotheses, investigations have been conducted on the feasibility of removal of charged particles from silicon wafers in electrolyte solutions of different ionic strengths irradiated with a megasonic field of different power densities. Cleaning experiments have been performed using potassium chloride (KCl) as a model electrolyte and silica particles as model contaminant particles. The cleaning performance in KCl solution has been compared to that in other electrolytes solutions such as sodium chloride, cesium chloride and lithium chloride. In order to characterize the cavitation events in KCl solutions, acoustic pressure and sonoluminescence measurements have been performed using hydrophone and cavitation probe respectively. The results indicate that particle removal efficiency (PRE) increases with KCl concentration and transducer power density and much lower power densities are required at higher KCl concentration for a comparable level of cleaning. Further, cleaning performances in NaCl and CsCl were found to be superior to those in KCl and LiCl solutions. Theoretical computations show that the removal forces due to CVP are much larger in magnitude than those due to IVP and are comparable to van der Waals forces.

Inconsistency often arises in real-world databases and, as a result, critical queries over dirty data may lead users to make ill-informed decisions. Functional dependencies (FDs) can be used to specify intended semantics of the underlying data and aid with the cleaning task. Enumerating and evaluating all the possible repairs to FD violations is infeasible, while approaches that produce a single repair or attempt to isolate the dirty portion of data are often too destructive or constraining. In this thesis, we leverage a recent advance in data cleaning that allows sampling from a well-defined space of reasonable repairs, and provide the user with a data management tool that gives uncertain query answers over this space. We propose a framework to compute probabilistic query answers as though each repair sample were a possible world. We show experimentally that queries over many possible repairs produce results that are more useful than other approaches and that our system can scale to large datasets.

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